Academic literature on the topic 'EIF3j'
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Journal articles on the topic "EIF3j"
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Herrmannová, Anna, Terezie Prilepskaja, Susan Wagner, et al. "Adapted formaldehyde gradient cross-linking protocol implicates human eIF3d and eIF3c, k and l subunits in the 43S and 48S pre-initiation complex assembly, respectively." Nucleic Acids Research 48, no. 4 (2019): 1969–84. http://dx.doi.org/10.1093/nar/gkz1185.
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Abstract One of the key roles of the 12-subunit eukaryotic translation initiation factor 3 (eIF3) is to promote the formation of the 43S and 48S pre-initiation complexes (PICs). However, particular contributions of its individual subunits to these two critical initiation reactions remained obscure. Here, we adapted formaldehyde gradient cross-linking protocol to translation studies and investigated the efficiency of the 43S and 48S PIC assembly in knockdowns of individual subunits of human eIF3 known to produce various partial subcomplexes. We revealed that eIF3d constitutes an important intermolecular bridge between eIF3 and the 40S subunit as its elimination from the eIF3 holocomplex severely compromised the 43S PIC assembly. Similarly, subunits eIF3a, c and e were found to represent an important binding force driving eIF3 binding to the 40S subunit. In addition, we demonstrated that eIF3c, and eIF3k and l subunits alter the efficiency of mRNA recruitment to 43S PICs in an opposite manner. Whereas the eIF3c knockdown reduces it, downregulation of eIF3k or eIF3l increases mRNA recruitment, suggesting that the latter subunits possess a regulatory potential. Altogether this study provides new insights into the role of human eIF3 in the initial assembly steps of the translational machinery.
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Sokabe, Masaaki, and Christopher S. Fraser. "A helicase-independent activity of eIF4A in promoting mRNA recruitment to the human ribosome." Proceedings of the National Academy of Sciences 114, no. 24 (2017): 6304–9. http://dx.doi.org/10.1073/pnas.1620426114.
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In the scanning model of translation initiation, the decoding site and latch of the 40S subunit must open to allow the recruitment and migration of messenger RNA (mRNA); however, the precise molecular details for how initiation factors regulate mRNA accommodation into the decoding site have not yet been elucidated. Eukaryotic initiation factor (eIF) 3j is a subunit of eIF3 that binds to the mRNA entry channel and A-site of the 40S subunit. Previous studies have shown that a reduced affinity of eIF3j for the 43S preinitiation complex (PIC) occurs on eIF4F-dependent mRNA recruitment. Because eIF3j and mRNA bind anticooperatively to the 43S PIC, reduced eIF3j affinity likely reflects a state of full accommodation of mRNA into the decoding site. Here, we have used a fluorescence-based anisotropy assay to quantitatively determine how initiation components coordinate their activities to reduce the affinity of eIF3j during the recruitment of mRNA to the 43S PIC. Unexpectedly, we show that a full reduction in eIF3j affinity for the 43S PIC requires an ATP-dependent, but unwinding-independent, activity of eIF4A. This result suggests that in addition to its helicase activity, eIF4A uses the free energy of ATP binding and hydrolysis as a regulatory switch to control the conformation of the 43S PIC during mRNA recruitment. Therefore, our results define eIF4A as a universal initiation factor in cap-dependent translation initiation that functions beyond its role in RNA unwinding.
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Nielsen, Klaus H., Leos Valášek, Caroah Sykes, Antonina Jivotovskaya, and Alan G. Hinnebusch. "Interaction of the RNP1 Motif in PRT1 with HCR1 Promotes 40S Binding of Eukaryotic Initiation Factor 3 in Yeast." Molecular and Cellular Biology 26, no. 8 (2006): 2984–98. http://dx.doi.org/10.1128/mcb.26.8.2984-2998.2006.
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ABSTRACT We found that mutating the RNP1 motif in the predicted RRM domain in yeast eukaryotic initiation factor 3 (eIF3) subunit b/PRT1 (prt1-rnp1) impairs its direct interactions in vitro with both eIF3a/TIF32 and eIF3j/HCR1. The rnp1 mutation in PRT1 confers temperature-sensitive translation initiation in vivo and reduces 40S-binding of eIF3 to native preinitiation complexes. Several findings indicate that the rnp1 lesion decreases recruitment of eIF3 to the 40S subunit by HCR1: (i) rnp1 strongly impairs the association of HCR1 with PRT1 without substantially disrupting the eIF3 complex; (ii) rnp1 impairs the 40S binding of eIF3 more so than the 40S binding of HCR1; (iii) overexpressing HCR1-R215I decreases the Ts− phenotype and increases 40S-bound eIF3 in rnp1 cells; (iv) the rnp1 Ts− phenotype is exacerbated by tif32-Δ6, which eliminates a binding determinant for HCR1 in TIF32; and (v) hcr1Δ impairs 40S binding of eIF3 in otherwise wild-type cells. Interestingly, rnp1 also reduces the levels of 40S-bound eIF5 and eIF1 and increases leaky scanning at the GCN4 uORF1. Thus, the PRT1 RNP1 motif coordinates the functions of HCR1 and TIF32 in 40S binding of eIF3 and is needed for optimal preinitiation complex assembly and AUG recognition in vivo.
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Wei, Li, Lijun Liu, Lin Chen, et al. "Interfering Eukaryotic Translation Initiation Factor 3 Subunit J Antisense RNA1 Inhibits the Proliferation, Migration, and Invasion of Lung Cancer A549 Cells by Regulating microRNA-330-5p." Nanoscience and Nanotechnology Letters 12, no. 9 (2020): 1099–105. http://dx.doi.org/10.1166/nnl.2020.3208.
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This study investigated whether long noncoding RNA interfering EIF3J antisense RNA1 (EIF3JAS1) could affect lung cancer A549 cells as well as the role of microRNA-330-5p (miR-330-5p) during this process. To this end, quantitative real-time polymerase chain reaction was used to measure EIF3J-AS1 and miR-330-5p expression in 39 lung cancer cases. Small interfering RNA targeting EIF3J-AS1 (si-EIF3J-AS1), as well as the miR-330-5p inhibitor, was transfected into lung cancer A549 cells. The outcomes of cell proliferation, clone formation, migration, invasion, and E- and N-cadherin expression were analyzed using CCK-8 kit, clone formation experiment, Transwell method, and Western blot. The targeted binding between EIF3J-AS1 and miR-330-5p was explored using the luciferase experiment. The results showed higher EIF3J-AS1 expression but lower miR-330-5p expression cancer tissues. Furthermore, interfering EIF3J-AS1 increased miR-330-5p and E-cadherin protein expression, leading to a reduction in the proliferation, clone formation, migration, invasion, and N-cadherin protein expression of lung cancer A549 cells. Meanwhile, Transfecting si-EIF3J-AS1 and the miR-330-5p inhibitor could increase the proliferation, clone formation, migration, invasion, and N-cadherin protein expression of lung cancer A549 cells, suggesting the targeted relationship of EIF3J-AS1 to miR-330-5p. In summary, EIF3J-AS1 was highly expressed in lung cancer tissues, and interfering EIF3J-AS1 inhibited the proliferation,migration, and invasion of A549 cells through negative regulation of miR-330-5p.
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Luo, Yuhao, Rui Zhou, Na Huang, Li Sun, and Wangjun Liao. "Effect of long non-coding RNA EIF3J-AS1 on multi-drug resistance and autophagy in gastric cancer." Journal of Clinical Oncology 35, no. 15_suppl (2017): e15581-e15581. http://dx.doi.org/10.1200/jco.2017.35.15_suppl.e15581.
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e15581 Background: Gastric cancer (GC) is a leading cause of cancer mortality worldwide, oxaliplatin and epirubicin based chemotherapy are one of the most important treatment options for GC patients. However, drug resistance, especially multi-drug resistance remains a major obstacle for successful chemotherapy. Recently, long non-coding RNAs (lncRNAs) have been widely identified to play emerging roles in diverse physiological and pathophysiological processes including drug resistance. Our previous bioinformatics analysis showed long non-coding RNA EIF3J-AS1 was a potential multi-drug resistance gene, but the underlying mechanism is still unknown. Methods: We generated oxaliplatin resistance cells (MGC803/OXA) and epirubicin resistance cells(MGC803/EPI) based on parental gastric cancer cells MGC803. Relative expression levels of EIF3J-AS1 were measured by qRT-PCR. Transmission electron microscopy was used to measure autophagosomes. Rapamycin was applied to inducing autophagy while chloroquine and 3-methyladenine were used to block autophagy. Protein level of autophagy related genes were examined by Western Blot. Coexpression genes of EIF3J-AS1 from TCGA RNA-seq datas were analyzed by cBiportal. RNA immunoprecipitation was used to analyze endogenous microRNAs and mRNAs. Results: EIF3J-AS1 was significantly upregulated in MGC803/OXA and MGC803/EPI cells compared with parental cells MGC803. EIF3J-AS1 inhibition increased chemosensitivity to both oxaliplatin and epirubicin. Moreover, EIF3J-AS1 silence lead to the decrease of autophagy. Autophagy related gene ATG14 was identified as a downstream target gene. EIF3J-AS1 promoted ATG14 expression by directly interacting with and increasing stability of ATG14 mRNA, On the other hand, EIF3J-AS1 competitively sponged miR-188-3p and promoted ATG14 expression in a ceRNA-dependent way. Conclusions: LncRNA EIF3J-AS1 is a crucial regulator of multi-drug resistance by inducing autophagy in gastric cancer. Targeting EIF3J-AS1/ATG14 axis might be a new paradigm for cancer therapeutics.
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ElAntak, Latifa, Andreas G. Tzakos, Nicolas Locker, and Peter J. Lukavsky. "Structure of eIF3b RNA Recognition Motif and Its Interaction with eIF3j." Journal of Biological Chemistry 282, no. 11 (2006): 8165–74. http://dx.doi.org/10.1074/jbc.m610860200.
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Aylett, Christopher H. S., Daniel Boehringer, Jan P. Erzberger, Tanja Schaefer, and Nenad Ban. "Structure of a Yeast 40S–eIF1–eIF1A–eIF3–eIF3j initiation complex." Nature Structural & Molecular Biology 22, no. 3 (2015): 269–71. http://dx.doi.org/10.1038/nsmb.2963.
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Chen, Xin, Zuyuan Yang, Chao Yang, Kan Xie, Weijun Sun, and Shengli Xie. "Sparse Gene Coexpression Network Analysis Reveals EIF3J-AS1 as a Prognostic Marker for Breast Cancer." Complexity 2018 (June 12, 2018): 1–12. http://dx.doi.org/10.1155/2018/1656273.
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Predictive and prognostic biomarkers facilitate the selection of treatment strategies that can improve the survival of patients. Accumulating evidence indicates that long noncoding RNAs (lncRNAs) play important roles in cancer progression, with diagnostic and prognostic potential. However, few prognostic lncRNAs are reported for breast cancer, and little is known about their functions that contribute to cancer pathogenesis. In this paper, we used weighted correlation network analysis (WGCNA) to construct networks containing noncoding and protein-coding genes based on their expression in 1097 breast cancer patients. The differentially expressed genes were significantly overlapped with gene modules regulating cell cycle and cell adhesion. The cell cycle-related lncRNAs were consistently downregulated in breast cancer. One lncRNA, EIF3J-AS1, is significantly associated with clinicopathological characteristics, including tumor size, lymph node metastasis, estrogen receptor (ER), and progesterone receptor (PR) status. Kaplan–Meier survival analysis revealed that EIF3J-AS1, a downregulated lncRNA in breast tumor, is a potential prognostic marker for breast cancer. EIF3J-AS1 may function in an estrogen-independent manner and could be inhibited by the compound FDI-6. Therefore, integrating sparse gene coexpression network and clinicopathological features can accelerate identification and functional characterization of novel prognostic lncRNAs in breast cancer.
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Chiu, Wen-Ling, Susan Wagner, Anna Herrmannová, et al. "The C-Terminal Region of Eukaryotic Translation Initiation Factor 3a (eIF3a) Promotes mRNA Recruitment, Scanning, and, Together with eIF3j and the eIF3b RNA Recognition Motif, Selection of AUG Start Codons." Molecular and Cellular Biology 30, no. 18 (2010): 4415–34. http://dx.doi.org/10.1128/mcb.00280-10.
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ABSTRACT The C-terminal domain (CTD) of the a/Tif32 subunit of budding yeast eukaryotic translation initiation factor 3 (eIF3) interacts with eIF3 subunits j/Hcr1 and b/Prt1 and can bind helices 16 to 18 of 18S rRNA, suggesting proximity to the mRNA entry channel of the 40S subunit. We have identified substitutions in the conserved Lys-Glu-Arg-Arg (KERR) motif and in residues of the nearby box6 element of the a/Tif32 CTD that impair mRNA recruitment by 43S preinitiation complexes (PICs) and confer phenotypes indicating defects in scanning and start codon recognition. The normally dispensable CTD of j/Hcr1 is required for its binding to a/Tif32 and to mitigate the growth defects of these a/Tif32 mutants, indicating physical and functional interactions between these two domains. The a/Tif32 CTD and the j/Hcr1 N-terminal domain (NTD) also interact with the RNA recognition motif (RRM) in b/Prt1, and mutations in both subunits that disrupt their interactions with the RRM increase leaky scanning of an AUG codon. These results, and our demonstration that the extreme CTD of a/Tif32 binds to Rps2 and Rps3, lead us to propose that the a/Tif32 CTD directly stabilizes 43S subunit-mRNA interaction and that the b/Prt1-RRM-j/Hcr1-a/Tif32-CTD module binds near the mRNA entry channel and regulates the transition between scanning-conducive and initiation-competent conformations of the PIC.
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Borgo, Christian, Cinzia Franchin, Valentina Salizzato, et al. "Protein kinase CK2 potentiates translation efficiency by phosphorylating eIF3j at Ser127." Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 1853, no. 7 (2015): 1693–701. http://dx.doi.org/10.1016/j.bbamcr.2015.04.004.
Full textDissertations / Theses on the topic "EIF3j"
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Borgo, Christian. "Coinvolgimento della proteinchinasi CK2 nella resistenza all'imatinib in cellule di leucemia mieloide cronica." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3421631.
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Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder of hematopoietic stem cells, characterized by clonal expansion of a primitive pluripotent stem cell with the consequence of the increasing number of granulocytes in the blood. A hallmark of CML is the Philadelphia chromosome (Ph+), originated from a reciprocal chromosomal translocation t(9;22)(q34;q11), that leads to the formation of the BCR/ABL1 fusion gene, which encodes for the constitutively active Bcr/Abl tyrosine kinase oncoprotein.
Imatinib (STI-571) selectively targets the Bcr/Abl oncoprotein and represents now the standard therapy in this disease. Despite its great efficacy, imatinib-resistance has emerged as a significant clinical issue. The cell line LAMA84 is a model of CML. In this thesis, we used two variants of LAMA84 cells: one is unable to survive and grow in presence of imatinib (LAMA84-S), while the other can grow in presence of 1.5 ÎμM imatinib (LAMA84-R).
The aim of this work was the analysis of the protein kinase CK2 in the LAMA84-S/R cell lines. Protein kinase CK2 is a ubiquitously and constitutively active Ser/Thr kinase, which phosphorylates several substrates implicated in key processes of cell life. CK2 is mostly present as a heterotetrameric structure composed of two catalytic α (44 kDa) and/or α' (38 kDa) and two regulatory subunits β (25 kDa).
The analysis by western blotting of the Bcr/Abl protein-level in various cellular lysates of LAMA84-S and LAMA84-R cells shows that the imatinib-resistance in these cells is associated with an amplification of BCR/ABL1 gene and an overexpression of Bcr/Abl. Moreover, the analysis of the CK2 cellular protein-level points up, unexpectedly, a kinase expression about two-fold higher in imatinib-resistant than in imatinib-sensitive cells. Both CK2α and CK2β subunits, but not CK2α', are upregulated.
The activity of the CK2 holoenzyme was then tested on the β-casein substrate or on the specific synthetic peptide R3AD2SD5, while that of the monomeric CK2α was detected by an in-gel kinase assay. Consistent with the CK2 protein-level, the activity of both holoenzyme and monomeric CK2α is higher in LAMA84-R cells as compared to LAMA84-S cells.
The immunoprecipitation of Bcr/Abl from cellular lysates of LAMA84-S/R cells shows that CK2 co-immunoprecipitates with Bcr/Abl only in imatinib-resistant cells. This outcome is also supported by the presence of Bcr/Abl in the CK2α-immunoprecipitates obtained from the same cellular lysates, and analyzed by western blotting and mass spectrometry.
Since the relationship between CK2α and Bcr/Abl suggests a potential phosphorylation of CK2 by this tyrosine kinase, an immunoprecipitation with anti-phospho-tyrosine (p-Tyr) antibody was performed from cellular lysates of LAMA84-S/R cells and the western-blotting analysis of the immunoprecipitates reveals the presence of CK2 only in LAMA84-R samples. CK2α Tyr-phosphorylation increases if the cells are treated with the protein tyrosine phosphatase, pervanadate.
To prove if CK2 Tyr-phosphorylation is mediated by CK2α autophosphorylation, as elsewhere described, or by Bcr/Abl catalyzed phosphorylation, LAMA84-R cells were treated for 24h with inhibitors specific for CK2 or Bcr/Abl. CK2α was immunoprecipitated from treated cells and analyzed for its p-Tyr immunostaining. While CX-4945, a selective inhibitor of CK2, currently in phase I of clinical trial in patients with solid tumors, does not affect p-Tyr-CK2α-phosphorylation, the Abl-inhibitor imatinib reduces the Tyr-phosphorylation of CK2α, suggesting that Bcr/Abl is most likely involved in CK2α tyrosine-phosphorylation in LAMA84-R cells.
To examine the potential effect of CK2 or Bcr/Abl activities on the two kinase interaction, LAMA84-R cells were treated with CX-4945, imatinib, the Abl allosteric inhibitor GNF-2, and the potent non-specific kinase inhibitor staurosporine. Only the treatment with the CK2 inhibitor CX-4945 strongly reduces the interaction between the two kinases.
To highlight the role of CK2 during cell proliferation, LAMA84-S/R cells were treated for 48 h with different concentrations of CX-4945 and their viability was measured using the MTT assay. The data suggest that the viability of both LAMA84-R and LAMA84-S cells decreases at increasing concentration of CX-4945, being the inhibitor more effective on the imatinib-resistant than the imatinib-sensitive cells. Experiments performed using combined CX-4945 and imatinib, demonstrated that while the viability of LAMA84-S cells treated with imatinib alone or in combination with CX-4945 is reduced in the same manner, the inhibition of CK2 activity by CX-4945 sensitizes resistant LAMA84 cells to low imatinib concentrations.
Finally, the occurrence of possible interactions between CK2 and other proteins was analyzed in imatinib-resistant cells. To this purpose, CK2α was immunoprecipitated from LAMA84-R cellular lysates and the co-immunoprecipitation of CK2 in the immunocomplexes was tested by in vitro kinase assays in the presence of [γ33P]ATP. The SDS-PAGE analysis of the radioactive samples evidenced a band, of about 35-38 KDa, incorporating 33P-radioactivity comparable to that corresponding to CK2β subunit. The mass spectrometry analysis demonstrated that the band corresponds to the subunit j of the eukaryotic translation initiation factor 3 (eIF3j) and the phosphorylated site was identified as the Ser127 (Q-E-E-S-D-L-E).
The mass spectrometry analysis of CK2α-immunoprecipitates highlighted the presence of other eIF3 subunits, such as b, f, l, g, h, k. The IF3b-immunoprecipitates obtained from LAMA84-R lysates contained both CK2α and CK2β subunits and the in vitro phosphorylation of eIF3b-immunoprecipitates in the presence [γ33P]ATP demonstrated that also eIF3b is a substrate of CK2.<br>La leucemia mieloide cronica (CML) è una malattia mieloproliferativa delle cellule ematopoietiche staminali, caratterizzata da un'espansione clonale di cellule staminali pluripotenti progenitrici con il conseguente incremento dei granulociti nel sangue. Un marcatore della CML è il cromosoma Philadelphia (Ph+), originato dalla traslocazione reciproca t(9;22)(q34;q11), che dà origine al gene di fusione BCR/ABL1, codificante per l'oncoproteina Bcr/Abl, una tirosin-chinasi costitutivamente attiva.
L'imatinib (STI-571) colpisce selettivamente l'oncoproteina Bcr/Abl e rappresenta la terapia standard d'inizio per questa patologia. Nonostante la sua grande efficacia, la resistenza all'imatinib è emersa come un significativo problema clinico. La linea cellulare LAMA84 è un modello della CML. In questa tesi, abbiamo usato due varianti di cellule LAMA84: una è incapace di sopravvivere e crescere in presenza di imatinib (LAMA84-S), mentre l'altra può crescere in presenza di 1,5 ÎμM imatinib (LAMA84-R).
Lo scopo di questo lavoro è stato l'analisi della proteinchinasi CK2 nelle cellule LAMA84-S/R. La proteinchinasi CK2 è un Ser/Thr-chinasi ubiquitaria e costitutivamente attiva, che fosforila svariati substrati implicati in processi chiave della vita cellulare. CK2 presenta generalmente una struttura eterotetramerica composta da due subunità catalitiche α (44 kDa) e/o α' (38 kDa) e due subunità regolatrici β (25 kDa).
L'analisi mediante western blot dei livelli proteici di Bcr/Abl in diversi lisati cellulari di cellule LAMA84-S e LAMA84-R mostra che la resistenza all'imatinib in queste cellule è associata all'amplificazione del gene BCR/ABL1 e alla sovraespressione di Bcr/Abl. Inoltre, l'analisi dei livelli proteici intracellulari di CK2 evidenzia, inaspettatamente, un'espressione della chinasi di circa due volte maggiore nelle cellule resistenti all'imatinib rispetto a quelle sensibili. Entrambe le subunità CK2α e CK2β, ma non CK2α', sono sovraespresse.
L'attività dell'oloenzima CK2 è stata saggiata sul substrato β-caseina o sul peptide specifico sintetico R3AD2SD5, mentre quella di CK2α monomerica è stata rilevata mediante un in-gel kinase assay. Coerentemente con il livello proteico di CK2, l'attività sia dell'oloenzima che di CK2α monomerica è maggiore nelle cellule LAMA84-R rispetto alle cellule LAMA84-S.
L'immunoprecipitazione di Bcr/Abl da lisati cellulari di cellule LAMA84-S/R mostra che CK2 immunoprecipita con Bcr/abl solo nelle cellule resistenti all'imatinib. Questo dato è supportato anche dalla presenza di Bcr/Abl negli immunoprecipitati di CK2α ottenuti dai medesimi lisati e analizzati mediante western blot e spettrometria di massa.
Dato che la relazione fra CK2α e Bcr/Abl suggerisce una potenziale fosforilazione di CK2 da parte della tirosin-chinasi, si è realizzata un'immunoprecipitazione con l'anticorpo anti-fosfo-tirosina (p-Tyr) da lisati di cellule LAMA84-S/R e l'analisi tramite western blot degli immunoprecipitati rileva la presenza di CK2 solo nei campioni delle LAMA84-R. La Tyr-fosforilazione di CK2α aumenta se le cellule sono trattate con l'inibitore delle tirosin-fosfatasi, pervanadato.
Per provare se la Tyr-fosforilazione di CK2 è mediata dall'autofosforilazione di CK2α, come descritto altrove, o è catalizzata da Bcr/Abl, le cellule LAMA84-R sono state trattate per 24 h con inibitori specifici per CK2 o Bcr/Abl. CK2α è stata immunoprecipitata dalle cellule trattate ed è stata analizzato il suo stato di Tyr-fosforilazione mediante western blot. Mentre il CX-4945, un inibitore selettivo per CK2, ora in fase I degli studi clinici su pazienti con tumori solidi, non ha effetto sulla p-Tyr-CK2α l'imatinib riduce la Tyr-fosforilazione di CK2α, suggerendo che Bcr/Abl è maggiormente coinvolto nella fosforilazione tirosinica di CK2α nelle cellule LAMA84-R.
Per esaminare il potenziale effetto di CK2 e Bcr/Abl nell'interazione delle due chinasi, le cellule LAMA84-R sono state trattate con il CX-4945, l'imatinib, l'inibitore allosterico di Abl GNF-2, e il potente inibitore chinasico non-specifico staurosporina. Solo il trattamento con l'inibitore di CK2, CX-4945, riduce l'interazione fra le due chinasi.
Per sottolineare il ruolo di CK2 durante la proliferazione cellulare, le cellule LAMA84-S/R sono state trattate per 48 h con differenti concentrazioni di CX-4945 e la vitalità cellulare di entrambe le cellule LAMA84-S e LAMA84-R è stata misurata mediante il saggio MTT. I dati suggeriscono che la viabilità di entrambe le linee cellulari decresce all'aumentare della concentrazione del CX-4945, con un maggior effetto dell'inibitore nelle cellule LAMA84-R. Esperimenti effettuati mediante la combinazione di CX-4945 e imatinib, dimostrano che mentre la vitalità delle cellule LAMA84-S trattate con l'imatinib da solo o in combinazione con il CX-4945 è ridotta in modo simile, l'inibizione dell'attività di CK2 da parte del CX-4945 sensibilizza le cellule LAMA84-R a basse concentrazioni di imatinib.
Infine, la possibile interazione fra CK2 e altre proteine è stata analizzata nelle cellule resistenti all'imatinib. A questo proposito, CK2α è stata immunoprecipitata da lisati di cellule LAMA84-R e la sua attività CK2 negli immunocomplessi è stata valutata mediante un saggio chinasico in presenza di [γ33P]ATP. L'analisi mediante SDS/PAGE dei campioni reattivi evidenzia una banda, di circa 35-38 kDa, 33P-fosforilata in modo comparabile alla banda corrispondente alla subunità CK2β autofosforilata. L'analisi di spettrometria di massa ha dimostrato che la banda corrisponde alla subunità j del fattore eucariotico 3 d'inizio della traduzione (eIF3j) e il sito di fosforilazione è stato identificato nella Ser127 (Q-E-E-S-D-L-E).
L'analisi di spettrometria di massa degli immunoprecipitati di CK2α ha messo in evidenza la presenza di altre subunità di eIF3: b, f, l, g, h, k. Gli immunoprecipitati di eIF3b ottenuti da lisati di cellule LAMA84-R contengono sia CK2α che CK2β e la fosforilazione in vitro degli immunoprecipitati di eIF3b in presenza di [γ33P]ATP ha dimostrato che anche eIF3b è un substrato di CK2.
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TRIA, VALERIA. "CHARACTERIZATION OF EIF3E TRANSCRIPT: ROLE IN MAMMARY DEVELOPMENT AND CARCINOGENESIS." Doctoral thesis, Università degli Studi di Milano, 2013. http://hdl.handle.net/2434/217466.
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Il gene EIF3E (eukaryotic translation initiation factor 3 subunit e) è stato identificato inizialmente in topo come sito di integrazione del virus MMTV (mouse mammary tumor virus). Nel genoma umano EIF3E è un gene di 45 Kb localizzato nella porzione 22-23 del braccio lungo del cromosoma 8 e codifica per un RNA messaggero di 1516 nucleotidi e una proteina di 445 amminoacidi (52 KDa). L’integrazione del virus MMTV negli introni (5, 9, 12) del gene EIF3E causa la trascrizione di RNA tronchi. L’espressione di tali trascritti tronchi è in grado di indurre un fenotipo tumorale sia in vitro che in vivo. Sebbene sia stata individuata l’esistenza di una correlazione tra il tumore mammario ed EIF3E, non è ancora noto l’esatto ruolo che il gene svolge nell’insorgenza e nella progressione del carcinoma mammario. Sono numerose le funzioni associate ad EIF3E nelle cellule eucariotiche. EIF3E è coinvolto nella regolazione dell’espressione proteica sia come subunità del complesso EIF3 (Eukaryotic translation Initiation Factor 3), sia controllando la qualità di specifici RNA messaggeri attraverso il nonsense-mediated decay (NMD) sia regolando il turnover di specifiche proteine. EIF3E è inoltre coinvolto nella regolazione dell’integrità e stabilità genomica in quanto coinvolto nel meccanismo del “DNA damage response”, nella replicazione del DNA e nella mitosi.
Questo progetto di dottorato è focalizzato sullo studio del gene EIF3E ed del suo coinvolgimento nella formazione e nella progressione del tumore mammario. Abbiamo analizzato attraverso RT-qPCR l’espressione di EIF3E in diversi tessuti umani non tumorali. EIF3E ha un livello di espressione più alto nella ghiandola mammaria rispetto ad altri tessuti, questo risultato suggerisce come EIF3E possa avere una peculiare funzione nella ghiandola mammaria e sue variazioni possano essere correlate al tumore al seno. Valutando l’espressione di EIF3E in tessuti normali e tumorali della ghiandola mammaria provenienti da diversi pazienti abbiamo osservato come l’espressione di EIF3E diminuisce nel tessuto tumorale rispetto al tessuto normale.
Attraverso esperimenti in vitro abbiamo dimostrato come la down-regolazione di EIF3E sia in grado di indurre un fenotipo tumorale in cellule primarie normali della ghiandola mammaria e aumentare la tumorigenicità nelle MCF7. Analizzando quale possa essere la funzione di EIF3E nella formazione e progressione tumorale abbiamo osservato come modificando l’espressione di EIF3E si causano cambiamenti nei livelli di alcuni mRNA, coinvolti in aspetti chiave della progressione tumorale .<br>The eukaryotic translation initiation factor 3 e-subunit (EIF3E) gene was originally identified in mouse as an integration site of the Mouse Mammary Tumour Virus (MMTV). EIF3E is a 45Kb gene localized to region q22-23 of the human chromosome 8, encodes a mRNA of 1516 nt that is translated into a 52KDa protein of 445 amino acids. Integration of MMTV into EIF3E introns (5, 9 or 12) causes the expression of truncated transcripts. These shortened EIF3E transcripts induce malignant transformation demonstrated both in vitro and in vivo. The exact nature of EIF3E involvement in tumorigenesis is not fully understood. The EIF3E protein controls various types of cellular processes in eukaryotic cells. Studies showed that EIF3E regulates protein expression through its role as a subunit of the eukaryotic translation initiation 3 complex, by controlling the quality of specific mRNAs by nonsense-mediate decay (NMD) and the process of the protein turnover. EIF3E is also involved in maintenance of genome integrity and stability by its role in DNA damage response, mitosis and replication.
This Ph.D. work focused on studying the involvement of EIF3E in the human breast cancer. We evaluated the EIF3E expression in different normal human tissues by RT-qPCR. We observed that EIF3E has higher expression levels in the human mammary gland compared to other tissues analyzed. We hypothesize that EIF3E deregulation has a role in breast cancer. Analyzing the EIF3E expression in normal and cancer breast tissues, we determined that the EIF3E expression level is lower in tumor samples compared to their healthy counterparts.
Down regulation of EIF3E was found to induce a malignant phenotype in normal primary cells and increase malignancy in MCF7 cells, respectively. We investigated the role of EIF3E in breast cancer initiation and progression. EIF3E modulation resulted in loss of control of the expression of specific mRNAs involved in key aspects in the cancer process.
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Benyelles, Maname. "Le rôle de l'oncoprotéine INT6 dans la maintenance des télomères." Thesis, Lyon, École normale supérieure, 2015. http://www.theses.fr/2015ENSL0978/document.
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La protéine INT6/EIF3E codée par le gène mammalien correspondant au site d’intégration du rétrovirus Mouse Mammary tumor virus (MMTV) n°6 (int-6), a été impliquée dans le cancer du sein chez la souris et l’homme. Malgré qu’INT6 soit une sous-unité du facteur d’initiation de la traduction eIF3, elle n’est pas essentielle pour la traduction générale mais pour l’expression d’ARNm spécifiques tel qu’il a été montré pour la traduction d’ARNm histones. Elle a aussi été impliquée dans la réplication d’ADN en stabilisant le facteur de licence de la réplication MCM7, dans la réponse aux dommages à l’ADN (DDR) et dans la voie du “nonsense-mediated mRNA decay“ (NMD). Par rapport à cette dernière activité j’ai étudié si INT6 pouvait spécifiquement intervenir au niveau de l’homéostasie des télomères en agissant sur les transcrits TERRA. La délétion d’INT6 par une approche d’ARN interférence révèle une augmentation des niveaux des ARN télomériques TERRA qui est dépendante du chromosome et du type cellulaire. Malgré qu’INT6 soit un facteur du NMD, elle n’agit pas sur la demi-vie des TERRA. Les expériences de DNA-FISH ont montré une augmentation des dommages aux télomères (TIF) dans les cellules en absence d’INT6. Les aberrations observées correspondent à des pertes de télomères (TFE) et des signaux multi-télomériques (MTS). Par la technique de digestion de la chromatine à la nucléase micrococcale, nous avons retrouvé une plus rapide accumulation des mono-nucléosomes aux télomères en absence d’INT6, suggérant un rôle dans la conformation de la chromatine télomérique. Ces résultats mettent en évidence INT6 comme un nouveau facteur régulateur de la stabilité des télomères<br>The INT6/EIF3E protein encoded by the mammalian integration site 6 (int-6) gene, has been implicated in mouse and human breast carcinogenesis. Although, INT6 is a subunit of the eIF3 translation initiation factor, it is not essential for bulk translation but for specific mRNAs expression as histone mRNA translation. It has also been implicated in DNA replication by stabilizing the DNA replication licensing factor MCM7, in DNA Damage Response (DDR) and in the Nonsense mRNA Decay (NMD) pathway. Relative to the latter activity, I investigated whether INT6 can specifically meddle in telomere homeostasis by acting on TERRA transcripts. Deletion of INT6 by RNA interference approach revealed an increase in the telomeric RNA TERRA levels which is depending on the chromosome and cellular type. Although INT6 is a NMD factor, it doesn’t change TERRA steady-state. DNA-FISH experiments showed an increase in Telomere Induced Foci (TIFs) in INT6 depleted cells. These aberrations correspond to Telomere Free Ends (TFE) and Multi-Telomeric signals (MTS) which implicate INT6 in DDR. By means of Microccocal Nuclease (MNase) mapping assay, we found a rapid accumulation of telomeric mono-nucleosomes in INT6-depleted cells, suggesting a role in telomeric chromatin structure. These findings evidenced that INT6 is a novel key player in telomere stability
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Raibon, Audrey. "Le facteur d'initiation de la traduction eIF3f dans le muscle squelettique : étude in vitro et obtention de modèles animaux." Thesis, Montpellier 1, 2013. http://www.theses.fr/2013MON1T023/document.
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Le facteur d'initiation de la traduction eIF3f est une des sous-unités constituant le facteur d'initiation de la traduction eIF3. Au niveau musculaire la surexpression de eIF3f dans les myotubes induit une hypertrophie associée à une augmentation de la synthèse protéique. A l'inverse, l'inhibition de l'expression de eIF3f entraîne une atrophie associée à une diminution de la synthèse protéique. Ce travail de thèse a permis (i) in vitro de mettre en évidence les fonctions inhibitrices du facteur eIF3f au cours de la prolifération des myoblastes C2C12 et par une étude transcriptomique sur les fractions polysomales de caractériser les ARNm recrutés par eIF3f dans des conditions hypertrophiques; et (ii) de créer des lignées de souris inactivées pour eIF3f (souris KO eIF3f) et surexprimant eIF3f dans le muscle (souris transgénique eIF3f K5-10R) afin d'étudier in vivo l'impact de la modification de l'expression de eIF3f sur la régulation de la masse musculaire<br>The eukaryotic initiation factor eIF3f is one of the subunits of the translation initiator complex eIF3 required for several steps in the initiation of mRNA translation. In skeletal muscle, recent studies have demonstrated that eIF3f overexpression in myotubes exerts a hypertrophic activity associated to an increase in protein synthesis. This thesis shed light on muscle eIF3f functions by (i) characterizing in vitro the antiproliferative activity of this factor in C2C12 myoblasts and the RNAs recruited by eIF3f on polysomal fractions in hypertrophied myotubes and (ii) generating mice strains inactivated for eIF3f (eIF3f KO mice) and overexpressing eIF3f specifically in muscle (eIF3f K5-10R transgenic mice) to study in vivo the impact of eIF3f modulation on the muscular mass homeostasis
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Guillon, Laurent. "Etude des facteurs du démarrage de la traduction eIF5B et eIF3." Phd thesis, Ecole Polytechnique X, 2008. http://pastel.archives-ouvertes.fr/pastel-00004650.
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Le démarrage de la traduction est un processus central dans toute cellule. L'étude des protéines assistant le ribosome pour réaliser cette étape, les facteurs de démarrage (Initiation Factors Ifs), permet d'obtenir des informations sur les mécanismes moléculaires complexes assurant la fidélité et l'efficacité du démarrage. La comparaison des jeux de facteurs protéiques dans les trois règnes du monde vivant a permis de mettre en évidence la présence de trois facteurs universellement conservés. Parmi ceux-ci, le facteur eucaryotique/archéen e/aIF5B, homologue au facteur bactérien IF2, stimule l'association des sous-unités ribosomales au même titre que chez les Bactéries. Néanmoins, l'universalité du facteur est limitée par l'absence d'interaction reportée entre le facteur e/aIF5B et l'ARNt initiateur alors que cette liaison est parfaitement caractérisée chez les Bactéries. Une partie de ce travail de thèse a permis d'étendre la similitude fonctionnelle entre les facteurs en mettant en évidence une liaison de l'ARNt initiateur méthionylé par le facteur e/aIF5B. Cette liaison présente des caractéristiques identiques à celle de l'ARNt initiateur méthionylé et formylé par le facteur bactérien IF2. Une deuxième partie du travail de thèse a concerné le facteur eIF3, le plus complexe du système de démarrage chez les Eucaryotes. Ce complexe de 13 sous-unités chez l'humain et de 5 sous-unités chez la levure n'a pas d'équivalent dans les autres domaines du vivant bien qu'il joue un rôle central et essentiel chez les Eucaryotes. La compréhension de ses fonctions est néanmoins fortement limitée par le manque d'information à l'échelle moléculaire sur les interactions entre les sous-unités le composant et avec ses autres facteurs partenaires. De plus, le facteur s'avère être impliqué dans de nombreux cancers, ce qui étend l'intérêt de son étude. Mon travail a permis de développer une bibliothèque de vecteurs permettant de coexprimer les différentes sous-unités ou des formes stabilisées des sous-unités du facteur eIF3 de levure chez la Bactérie Escherichia coli. La purification des sous-unités isolées et de différents sous-complexes nous permet d'envisager la résolution de la structure du facteur et de son organisation par une approche alliant la cristallographie et la microscopie électronique.
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Wang, Xiaoshan. "Regulation of eIF3-Paip1 interaction by extracellular stimuli and phosphorylation status." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86958.
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The tertiary interaction of poly(A)-binding protein (PABP), with eukaryotic translation initiation factor 4G (eIF4G) and 3'poly(A) tail of mRNA acts to stimulate translation initiation. Subsequently, the interaction of PABP-interacting protein 1 (Paip1) with PABP and eukaryotic translation initiation factor 3 (eIF3) (via the eIF3g subunit) further stimulates translation. Here, we demonstrate that the interaction of eIF3 and Paip1 is regulated by the presence of amino acids through an mTORC1 dependent signaling pathway. This interaction is inhibited by addition of mTORC1 signaling pathway inhibitors; such as rapamycin and wortmannin. Paip1 binds to eIF3g and this subunit can be phosphorylated on either Thr41 or Ser42. However, we find that phosphorylation on these sites is not stimulated by amino acids, nor does it act to enhance eIF3-Paip1 interaction. On the other hand, we show that S6 ribosomal protein kinase (S6K) positively regulates the interaction of eIF3 and Paip1 and we propose that S6K acts as a putative kinase for eIF3. The studies of the regulation of eIF3-Paip1 interaction will lead to better understanding the translation process.<br>L'interaction tertiaire entre la protéine PABP (poly(A)-binding protein), le facteur d'initiation de la traduction eucaryote 4G (eIF4G), et la queue poly(A) des ARN messagers, stimule l'initiation de la traduction. De plus, l'interaction entre la protéine qui interagit avec PABP, Paip1 (PABP-interacting protein 1), et le facteur d'initiation de la traduction eucaryote 3 (eIF3) (par sa sous-unité g), induit la traduction de façon plus élevée. Dans cette thèse, nous démontrons que l'interaction entre l'eIF3 et Paip1 est régulée par la présence d'acides aminées, et que cette interaction est dépendante de la voie signalétique contrôlée par mTORC1. En effet, les inhibiteurs de cette voie signalétique comme la rapamycin et la wortmannin bloquent l'interaction. Comme Paip1 s'attache directement à la sous-unité g de l'eIF3 et que cette dernière peut être phosphorylée sur la thréonine 41 ou la sérine 42, nous avons étudié le rôle la phosphorylation de eIF3g sur l'interaction entre les deux protéines. Nous démontrons que cette phosphorylation n'est pas stimulée par l'addition d'acides aminées et qu'elle n'induit pas une plus grande interaction entre eIF3 et Paip1. Par contre, nous observons que la kinase S6K (S6 ribosomal protein kinase), régule de façon positive l'interaction entre eIF3 et Paip1, et nous suggérons que cette kinase agit sur eIF3. Cette étude sur les rôles et actions de eIF3 et Paip1 aide à de plus grandes connaissances sur la régulation de l'initiation de la traduction eucaryote.
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Morais, Ana Theresa Silveira de [UNESP]. "Caracterização da interação entre a proteínas NS5 do vírus da febre amarela e EIF3L." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/103873.
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morais_ats_dr_sjrp.pdf: 1276143 bytes, checksum: 62a89d8b555ac92b5faf4baa19e4db2f (MD5)<br>O vírus da Febre Amarela (YFV) pertence ao gênero Flavivirus e causa uma importante doença. Nos últimos anos, uma alarmante ressurgência da circulação viral e expansão do vírus em áreas endêmicas têm sido detectadas na África e América do Sul. NS5 é uma proteína viral não estrutural com duas atividades essenciais para a replicação viral, uma de metiltransferase e outra de RNA Polimerase dependente de RNA (RdRp). Para o melhor entendimento dos mecanismos de replicação viral, interações entre NS5 e proteínas celulares têm sido amplamente estudadas. Assim, os objetivos desse estudo foram caracterizar a interação da proteína NS5 e eIF3L, avaliar a função de eIF3L na replicação do vírus da febre amarela, e caracterizar estruturalmente a proteína eIF3L. Métodos. Para identificar a interação de NS5 YFV com eIF3L, foi realizado ensaios em sistema duplo-híbrido usando RdRp NS5 YFV contra eIF3L. Para o mapeamento da interação, foram construídos mutantes deletantes de RNApol e analisados em sistema duplo-híbrido. A região de interação de RNApol foi segmentada em três fragmentos e analisada na presença de eIF3L. Para mapear os resíduos de NS5 críticos para a interação, foi realizada mutagênese sítio-dirigida no segmento 3 de ID. A interação foi analisada em ensaios in vitro e em cultura de células de mamíferos. A significância de eIF3L para a replicação do YFV foi investigada usando superexpressão de eIF3L em células BHK21-RepYF17D LucNeoIres. A proteína eIF3L foi purificada usando uma combinação de cromatografia de afinidade e de exclusão molecular para subsequente caracterização estrutural. Resultados. Nesse estudo, foi caracterizada a interação de NS5 com o fator eucariótico de início de tradução...<br>Yellow fever virus (YFV) belongs to the Flavivirus genus and causes an important disease. An alarming resurgence of viral circulation and expansion of the YFV endemic zones have been detected in Africa and South America in recent years. NS5 is a viral protein that contains the methyltransferase and RNA-dependent RNA polymerase domains, which are essential during viral replication. Interactions among NS5 and cellular proteins have been studied for the understanding of viral replication. The aim of this study was to characterize the interaction of NS5 protein with EIF3L and evaluate the role of EIF3L in yellow fever replication. Methods. To identify the interaction of YFV NS5 with cellular proteins, we performed a two-hybrid screen using YFV NS5 RdRp domain as bait and a human cDNA library. For mapping the interaction, RNApol deletions mutants were performed and analyses in two-hybrid system. The RNApol region of interaction was segmented in three fragments and analyses into yeast containing eIF3L. To map residues of NS5 that are critical for its interaction, we performed a site-direct mutagenesis in segment 3 of ID. The interaction was confirmed in vitro assays and by in vivo coimmunoprecipitations. The significance of eIF3L for replication of YFV was investigated using overexpression of eIF3L in BHK21-RepYF17D LucNeoIres cells. eIF3L was purified using a combination of affinity and subsequent size exclusion chromatography for subsequent structural characterization. Results. In this work we describe and characterize the interaction of NS5 with the translation factor eIF3L. The interaction between NS5 and eIF3L was confirmed by in vitro binding and in vivo coimmunoprecipitation assays. This interaction occurs in a region (Interaction Domain of RNApol domain) that is conserved in several... (Complete abstract click electronic access below)
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Morais, Ana Theresa Silveira de. "Caracterização da interação entre a proteínas NS5 do vírus da febre amarela e EIF3L /." São José do Rio Preto : [s.n.], 2012. http://hdl.handle.net/11449/103873.
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Orientador: Maurício Lacerda Nogueira<br>Banca: Fátima Pereira de Souza<br>Banca: Cleslei Fernando Zanelli<br>Banca: Eurico de Arruda Neto<br>Banca: Luciana Barros de Arruda<br>Resumo: O vírus da Febre Amarela (YFV) pertence ao gênero Flavivirus e causa uma importante doença. Nos últimos anos, uma alarmante ressurgência da circulação viral e expansão do vírus em áreas endêmicas têm sido detectadas na África e América do Sul. NS5 é uma proteína viral não estrutural com duas atividades essenciais para a replicação viral, uma de metiltransferase e outra de RNA Polimerase dependente de RNA (RdRp). Para o melhor entendimento dos mecanismos de replicação viral, interações entre NS5 e proteínas celulares têm sido amplamente estudadas. Assim, os objetivos desse estudo foram caracterizar a interação da proteína NS5 e eIF3L, avaliar a função de eIF3L na replicação do vírus da febre amarela, e caracterizar estruturalmente a proteína eIF3L. Métodos. Para identificar a interação de NS5 YFV com eIF3L, foi realizado ensaios em sistema duplo-híbrido usando RdRp NS5 YFV contra eIF3L. Para o mapeamento da interação, foram construídos mutantes deletantes de RNApol e analisados em sistema duplo-híbrido. A região de interação de RNApol foi segmentada em três fragmentos e analisada na presença de eIF3L. Para mapear os resíduos de NS5 críticos para a interação, foi realizada mutagênese sítio-dirigida no segmento 3 de ID. A interação foi analisada em ensaios in vitro e em cultura de células de mamíferos. A significância de eIF3L para a replicação do YFV foi investigada usando superexpressão de eIF3L em células BHK21-RepYF17D LucNeoIres. A proteína eIF3L foi purificada usando uma combinação de cromatografia de afinidade e de exclusão molecular para subsequente caracterização estrutural. Resultados. Nesse estudo, foi caracterizada a interação de NS5 com o fator eucariótico de início de tradução... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: Yellow fever virus (YFV) belongs to the Flavivirus genus and causes an important disease. An alarming resurgence of viral circulation and expansion of the YFV endemic zones have been detected in Africa and South America in recent years. NS5 is a viral protein that contains the methyltransferase and RNA-dependent RNA polymerase domains, which are essential during viral replication. Interactions among NS5 and cellular proteins have been studied for the understanding of viral replication. The aim of this study was to characterize the interaction of NS5 protein with EIF3L and evaluate the role of EIF3L in yellow fever replication. Methods. To identify the interaction of YFV NS5 with cellular proteins, we performed a two-hybrid screen using YFV NS5 RdRp domain as bait and a human cDNA library. For mapping the interaction, RNApol deletions mutants were performed and analyses in two-hybrid system. The RNApol region of interaction was segmented in three fragments and analyses into yeast containing eIF3L. To map residues of NS5 that are critical for its interaction, we performed a site-direct mutagenesis in segment 3 of ID. The interaction was confirmed in vitro assays and by in vivo coimmunoprecipitations. The significance of eIF3L for replication of YFV was investigated using overexpression of eIF3L in BHK21-RepYF17D LucNeoIres cells. eIF3L was purified using a combination of affinity and subsequent size exclusion chromatography for subsequent structural characterization. Results. In this work we describe and characterize the interaction of NS5 with the translation factor eIF3L. The interaction between NS5 and eIF3L was confirmed by in vitro binding and in vivo coimmunoprecipitation assays. This interaction occurs in a region (Interaction Domain of RNApol domain) that is conserved in several... (Complete abstract click electronic access below)<br>Doutor
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Bertorello, Juliette. "Reprogrammation traductionnelle par eIF3 liée à la résistance aux traitements des glioblastomes." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30096.
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La résistance intrinsèque aux thérapies actuelles, conduisant à une rechute quasi systématique des patients, est une caractéristique des glioblastomes multiformes (GBM), la tumeur cérébrale la plus courante et la plus agressive. Comprendre les mécanismes sous-jacents d'une telle tumeur maligne est donc un besoin médical urgent. Il a été démontré par de nombreux travaux que la dérégulation de la machinerie de traduction des ARNm, notamment pendant l'étape d'initiation, contribue à la transformation maligne et à la progression des cancers en partie via une traduction sélective des transcrits spécifiques impliqués dans le développement et la survie des cellules cancéreuses. Mes travaux de thèse se sont concentrés sur le facteur eIF3, un complexe multimérique participant à l'initiation de la traduction et fréquemment dérégulé dans les GBM. Nos travaux montrent que l'expression dérégulée d'eIF3e, la sous-unité (e) du complexe eIF3, dans des régions de GBM spécifiques, impacte la synthèse de protéines nécessaires à la survie des cellules cancéreuses. En particulier, eIF3e restreint l'expression des protéines impliquées dans la réponse au stress cellulaire et augmente l'expression des marqueurs de cellules souches. Nos résultats montrent également que les effets d'activation et de répression d'eIF3e sur la traduction pourraient s'expliquer en partie par un modèle de liaison distinct d'eIF3e, d'eIF3d et de DDX3X (une ARN hélicase) sur les ARNm cibles. Finalement, l'ensemble des données obtenues permettent de mieux appréhender comment l'hétérogénéité intratumorale de l'expression de eIF3 aboutit à l'activation de voies de signalisation propres à chaque région tumorale dans les GBM, notion essentielle à prendre en compte dans l'élaboration de futurs traitements plus ciblés et plus personnalisés pour les patients<br>The intrinsic resistance to current therapies, leading to an almost systematic relapse of patients, is a characteristic of glioblastomas (GBM), the most common and aggressive brain tumor. Understanding the underlying mechanisms of such a malignant tumor is therefore an urgent medical need. Several studies support the notion of a deregulation of the translation machinery, in particular during the initiation stage, contributes to the malignant transformation and progression of cancers, in part via a selective translation of the specific transcripts involved in the development and maintenance of cancer cells. Our work focuses on the eIF3 factor, a multimeric complex participating in the initiation of translation and frequently deregulated in GBM. Our results show that the deregulated expression of eIF3e, the subunit (e) of the eIF3 complex, in specific GBM regions, could influence the synthesis of specific proteins impacting the development of the disease. In particular, eIF3e restricts the expression of proteins involved in the response to cellular stress and increases the expression of stem cell markers. Our results also show that the activation and repression effects of eIF3e on translation could be partially explained by a distinct binding model of eIF3e, eIF3d and DDX3X (a RNA helicase) on target mRNAs. Finally, the data obtained allow us to better understand how the intratumor heterogeneity of eIF3 expression results in the activation of signaling pathways specific to each tumor region in GBM, an essential concept to take into account in the development of future more targeted and personalized treatments for patient
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Lagirand-Cantaloube, Julie. "MyoD et eIF3f : cibles majeures du complexe ubiquitine-ligase SCFMAFbx au cours de l'atrophie musculaire." Paris 11, 2008. http://www.theses.fr/2008PA11T020.
Full textBook chapters on the topic "EIF3j"
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Hershey, John W. B. "eIF3." In Translation and Its Regulation in Cancer Biology and Medicine. Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-017-9078-9_8.
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Choudhuri, Avik, Anirban Ray, Arunima Biswas, and Umadas Maitra. "eIF3." In Encyclopedia of Signaling Molecules. Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4614-6438-9_101984-1.
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Yin, Ji-Ye, Zizheng Dong, and Jian-Ting Zhang. "eIF3 Regulation of Protein Synthesis, Tumorigenesis, and Therapeutic Response." In Methods in Molecular Biology. Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-6518-2_9.
Full textConference papers on the topic "EIF3j"
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Tumia, Rima A. "Abstract 3029: Role of eIF3a expression in cellular sensitivity to radiation treatment." In Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA. American Association for Cancer Research, 2015. http://dx.doi.org/10.1158/1538-7445.am2015-3029.
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Cui, Jia-Jia, Lei-Yun Wang, and Ji-Ye Yin. "Abstract 1407: Translational regulation of RPA2 via IRES by UNR and eIF3a." In Proceedings: AACR Annual Meeting 2017; April 1-5, 2017; Washington, DC. American Association for Cancer Research, 2017. http://dx.doi.org/10.1158/1538-7445.am2017-1407.
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Xu, Pengfei, and Dake Li. "Abstract 6000: eIF3A regulate the Warburg effect via ENO1 in cervical cancer cells." In Proceedings: AACR Annual Meeting 2020; April 27-28, 2020 and June 22-24, 2020; Philadelphia, PA. American Association for Cancer Research, 2020. http://dx.doi.org/10.1158/1538-7445.am2020-6000.
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Yin, Jiye, Zizheng Dong, Zhaoqian Liu, and Jianting Zhang. "Abstract 1749: Role of eIF3a in DNA repair and lung cancer chemo sensitivity." In Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL. American Association for Cancer Research, 2011. http://dx.doi.org/10.1158/1538-7445.am2011-1749.
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Wang, Hong, Xuejiao Wang, Yuanbin Ru, Mark R. Conaway, Jeffery S. Kieft, and Dan Theodorescu. "Abstract 4200: Translation initiation factor eIF3b expression and its role in cancer cell growth and metastases." In Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL. American Association for Cancer Research, 2012. http://dx.doi.org/10.1158/1538-7445.am2012-4200.
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Shi, Jiaqi, Brittany Silverman, and Lili Zhao. "Abstract B26: Altered eIF3f subcellular localization and expression in pancreatic ductal adenocarcinomas and its precursor lesions." In Abstracts: AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; May 12-15, 2016; Orlando, FL. American Association for Cancer Research, 2016. http://dx.doi.org/10.1158/1538-7445.panca16-b26.
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Wu, Xiling, Yen-Lin Chu, and Chengtao Her. "Abstract 640: Human MutS homologue 4 (hMSH4) interacts with eIF3f and inhibits NHEJ-mediated DNA repair." In Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC. American Association for Cancer Research, 2013. http://dx.doi.org/10.1158/1538-7445.am2013-640.
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Paluncic, Jasmina, Darius J. R. Lane, Federica Saletta, Yohan S. Rahmanto, Zaklina Kovacevic, and Des R. Richardson. "Abstract B212: N-myc downstream regulated 1 (NDRG1) is regulated by eukaryotic initiation factor 3a (eIF3a) during cellular stress caused by iron depletion." In Abstracts: AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; October 26-30, 2017; Philadelphia, PA. American Association for Cancer Research, 2018. http://dx.doi.org/10.1158/1535-7163.targ-17-b212.
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Cuesta, Rafael, and Marina K. Holz. "Abstract B28: Estrogen receptor alpha (ERa) promotes protein synthesis by fine-tuning the expression of the eukaryotic translation initiation factor 3 subunit f (eIF3f)." In Abstracts: AACR Special Conference on Targeting PI3K/mTOR Signaling; November 30-December 8, 2018; Boston, MA. American Association for Cancer Research, 2020. http://dx.doi.org/10.1158/1557-3125.pi3k-mtor18-b28.
Full textReports on the topic "EIF3j"
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Chamovitz, Daniel, and Albrecht Von Arnim. Translational regulation and light signal transduction in plants: the link between eIF3 and the COP9 signalosome. United States Department of Agriculture, 2006. http://dx.doi.org/10.32747/2006.7696515.bard.
Full textAbstract:
The COP9 signalosome (CSN) is an eight-subunit protein complex that is highly conserved among eukaryotes. Genetic analysis of the signalosome in the plant model species Arabidopsis thaliana has shown that the signalosome is a repressor of light dependent seedling development as mutant Arabidopsis seedlings that lack this complex develop in complete darkness as if exposed to light. These mutant plants die following the seedling stage, even when exposed to light, indicating that the COP9 signalosome also has a central role in the regulation of normal photomorphogenic development. The biochemical mode of action of the signalosome and its position in eukaryotic cell signaling pathways is a matter of controversy and ongoing investigation, and recent results place the CSN at the juncture of kinase signaling pathways and ubiquitin-mediated protein degradation. We have shown that one of the many CSN functions may relate to the regulation of translation through the interaction of the CSN with its related complex, eukaryotic initiation factor (eIF3). While we have established a physical connection between eIF3 subunits and CSN subunits, the physiological and developmental significance of this interaction is still unknown. In an effort to understand the biochemical activity of the signalosome, and its role in regulating translation, we originally proposed to dissect the contribution of "h" subunit of eIF3 (eIF3h) along the following specific aims: (i) Isolation and phenotypic characterization of an Arabidopsis loss-of-function allele for eIF3h from insertional mutagenesis libraries; (ii) Creation of designed gain and loss of function alleles for eIF3h on the basis of its nucleocytoplasmic distribution and its yeast-two-hybrid interactions with other eIF3 and signalosome partner proteins; (iii) Determining the contribution of eIF3h and its interaction with the signalosome by expressing specific mutants of eIF3h in the eIF3h- loss-of function background. During the course of the research, these goals were modified to include examining the genetic interaction between csn and eif3h mutations. More importantly, we extended our effort toward the genetic analysis of mutations in the eIF3e subunit, which also interacts with the CSN. Through the course of this research program we have made several critical scientific discoveries, all concerned with the apparent diametrically opposed roles of eIF3h and eIF3e. We showed that: 1) While eIF3e is essential for growth and development, eIF3h is not essential for growth or basal translation; 2) While eIF3e has a negative role in translational regulation, eIF3h is positively required for efficient translation of transcripts with complex 5' UTR sequences; 3) Over-accumulation of eIF3e and loss-of-function of eIF3h both lead to cop phenotypes in dark-grown seedlings. These results were published in one publication (Kim et al., Plant Cell 2004) and in a second manuscript currently in revision for Embo J. Are results have led to a paradigm shift in translation research – eIF3 is now viewed in all systems as a dynamic entity that contains regulatory subuits that affect translational efficiency. In the long-term agronomic outlook, the proposed research has implications that may be far reaching. Many important plant processes, including developmental and physiological responses to light, abiotic stress, photosynthate, and hormones operate in part by modulating protein translation [23, 24, 40, 75]. Translational regulation is slowly coming of age as a mechanism for regulating foreign gene expression in plants, beginning with translational enhancers [84, 85] and more recently, coordinating the expression of multiple transgenes using internal ribosome entry sites. Our contribution to understanding the molecular mode of action of a protein complex as fundamental as eIF3 is likely to lead to advances that will be applicable in the foreseeable future.
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Chamovitz, Daniel A., and Albrecht G. Von Arnim. eIF3 Complexes and the eIF3e Subunit in Arabidopsis Development and Translation Initiation. United States Department of Agriculture, 2009. http://dx.doi.org/10.32747/2009.7696545.bard.
Full textAbstract:
The original working hypothesis of our proposal was that The “e” subunit of eIF3 has multiple functions from both within the nucleus and in the cytoplasm. Within this model, we further hypothesized that the “e” subunit of eIF3 functions in translation as a repressor. We proposed to test these hypotheses along the following specific aims: 1) Determine the subcellular localization of the interaction between eIF3e and other eIF3 subunits, or the COP9 signalosome. 2) Elucidate the biological significance of the varied subcellular localizations of eIF3e through generating Arabidopsis eIF3e alleles with altered subcellular localization. 3.) Purify different eIF3e complexes by tandem affinity purification (TAP). 4) Study the role of eIF3e in translational repression using both in vitro and in planta assays. eIF3 is an evolutionarily ancient and essential component of the translational apparatus in both the plant and animal kingdoms. eIF3 is the largest, and in some ways the most mysterious, of the translation factors. It is a multi-subunit protein complex that has a structural/scaffolding role in translation initiation. However, despite years of study, only recently have differential roles for eIF3 in the developmental regulation of translation been experimentally grounded. Furthermore, the roles of individual eIF3 subunits are not clear, and indeed some, such as the “e” subunit may have roles independent of translation initiation. The original three goals of the proposal were technically hampered by a finding that became evident during the course of the research – Any attempt to make transgenic plants that expressed eIF3e wt or eIF3e variants resulted in seedling lethality or seed inviability. That is, it was impossible to regenerate any transgenic plants that expressed eIF3e. We did manage to generate plants that expressed an inducible form of eIF3e. This also eventually led to lethality, but was very useful in elucidating the 4th goal of the research (Yahalom et al., 2008), where we showed, for the first time in any organism, that eIF3e has a repressory role in translation. In attempt to solve the expression problems, we also tried expression from the native promoter, and as such analyzed this promoter in transgenic plants (Epel, 2008). As such, several additional avenues were pursued. 1) We investigated protein-protein interactions of eIF3e (Paz-Aviram et al., 2008). 2) The results from goal #4 led to a novel hypothesis that the interaction of eIF3e and the CSN meets at the control of protein degradation of nascent proteins. In other words, that the block in translation seen in csn and eIF3e-overexpressing plants (Yahalom et al., 2008) leads to proteasome stress. Indeed we showed that both over expression of eIF3e and the csn mutants lead to the unfolded protein response. 3) We further investigated the role of an additional eIF3 subunit, eIF3h, in transalational regulation in the apical meristem (Zhou et al., 2009). Epel, A. (2008). Characterization of eIF3e in the model plant Arabidopsis thaliana. In Plant Sciences (Tel Aviv, Tel Aviv University). Paz-Aviram, T., Yahalom, A., and Chamovitz, D.A. (2008). Arabidopsis eIF3e interacts with subunits of the ribosome, Cop9 signalosome and proteasome. Plant Signaling and Behaviour 3, 409-411. Yahalom, A., Kim, T.H., Roy, B., Singer, R., von Arnim, A.G., and Chamovitz, D.A. (2008). Arabidopsis eIF3e is regulated by the COP9 signalosome and has an impact on development and protein translation. Plant J 53, 300-311. Zhou, F., Dunlap, J.R., and von Arnim, A.G. The translation initiation factor subunit eIF3h is .1 involved in Arabidopsis shoot apical meristem maintenance and auxin response. (submitted to Development).
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von Arnim, Albrecht G. Eukaryotic initiation factor 3 (eIF3) and 5’ mRNA leader sequences as agents of translational regulation in Arabidopsis. Final report. Office of Scientific and Technical Information (OSTI), 2015. http://dx.doi.org/10.2172/1169186.
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Chamovitz, Daniel, and Xing-Wang Deng. Morphogenesis and Light Signal Transduction in Plants: The p27 Subunit of the COP9-Complex. United States Department of Agriculture, 1997. http://dx.doi.org/10.32747/1997.7580666.bard.
Full textAbstract:
Plants monitor environmental signals and modulate their growth and development in a manner optimal for the prevailing light conditions. The mechanisms by which plants transduce light signals and integrate them with other environmental and developmental signals to regulate plant pattern development are beginning to be unraveled. A large body of knowledge has accumulated regarding the roles of specific photoreceptors in perceiving light signals, and about the downstream developmental responses responding to light (Batschauer, 1999; Chamovitz and Deng, 1996; Deng and Quail, 1999). Still, little is know about the molecular mechanisms connecting the photoreceptors to development, and how these developmental pathways are integrated with additional developmental regulatory pathways to modulate growth. The multi-subunit protein complex COP9 signalosome (previously referred to as the "COP9 complex") has a central role in mediating the light control of plant development, and in general developmental regulation. Arabidopsis mutants that lack this complex develop photomorphogenically even in the absence of light signals (reviewed in Chamovitz and Deng 1996, 1997). Various genetic studies have indicated that the COP9 signalosome acts at the nexus of upstream signals transduced from the individual photoreceptors, and specific downstream signaling pathways. Thus the COP9 signalosome was hypothesized to be a master repressor of photomorphogenesis, and that light acts to abrogate this repression. However, the COP9 signalosome has roles beyond the regulation of photomorphogenesis as all mutants lacking this complex die following early seedling development, and an essentially identical complex has also been detected in animal systems (Chamovitz and Deng, 1995; Seeger et al., 1998; Wei et al., 1998). Our long term objective is to determine the role of the COP9 signalosome in controlling plant development. In this research project we showed that this complex contains at least eight subunits (Karniol et al., 1998; Serino et al., 1999) and that the 27 kD subunit is encoded by the FUS5 locus (Karniol et al., 1999). The FUS5 subunit also has a role extraneous to the COP9 signalosome, and differential kinase activity has been implicated in regulating FUSS and the COP9 signalosome (Karniol et al., 1999). We have also shown that the COP9 signalosome may work together with the translational-regulator eIF3. Our study of the COP9 signalosome is one of the exciting examples of plant science leading the way to discoveries in basic animal science (Chamovitz and Deng, 1995; Karniol and Chamovitz, 2000; Wei and Deng, 1999).